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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on BaSr2Mg(SiO4)2 by Materials Project

BaSr2Mg(SiO4)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share edges with six equivalent BaO12 cuboctahedra, edges with six equivalent SiO4 tetrahedra, and faces with two equivalent MgO6 octahedra. There are six shorter (2.84 Å) and six longer (3.21 Å) Ba–O bond lengths. Sr2+ is bonded in a 1-coordinate geometry to ten O2- atoms. There are a spread of Sr–O bond distances ranging from 2.39–2.86 Å. Mg2+ is bonded to six equivalent O2- atoms to form MgO6 octahedra that share corners with six equivalent SiO4 tetrahedra and faces with two equivalent BaO12 cuboctahedra. All Mg–O bond lengths are 2.10 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with three equivalent MgO6 octahedra and edges with three equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 13°. There is one shorter (1.62 Å) and three longer (1.66 Å) Si–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to three equivalent Ba2+, one Sr2+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, three equivalent Sr2+, one Mg2+, and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba3SrMg2(Si2O7)2 by Materials Project

Ba3SrMg2(Si2O7)2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.73–2.96 Å. In the second Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.67–2.97 Å. Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.53–2.89 Å. Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with four SiO4 tetrahedra. There is one shorter (1.98 Å) and three longer (1.99 Å) Mg–O bond length. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent MgO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent MgO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.63–1.69 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent MgO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.69 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, one Sr2+, and two equivalent Si4+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ba2+ and two Si4+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ba2+, one Sr2+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to two Ba2+, one Sr2+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+ and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, one Sr2+, one Mg2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+, one Sr2+, one Mg2+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two Ba2+, one Mg2+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Ba2+, one Mg2+, and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaSrMgSi2O7 by Materials Project

SrBaMgSi2O7 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.71–2.97 Å. Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.56–2.88 Å. Mg2+ is bonded to four O2- atoms to form MgO4 tetrahedra that share corners with four SiO4 tetrahedra. There is three shorter (1.98 Å) and one longer (1.99 Å) Mg–O bond length. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent MgO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.69 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one SiO4 tetrahedra and corners with two equivalent MgO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.62–1.69 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, one Sr2+, and two Si4+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sr2+, one Mg2+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Mg2+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Ba2+, one Sr2+, one Mg2+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Ba2+, one Sr2+, one Mg2+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one Ba2+, two equivalent Sr2+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted single-bond geometry to two equivalent Ba2+, one Sr2+, and one Si4+ atom.

36 MATERIALS SCIENCE↗